Temperature dependence of the energy bandgap of multi-layer hexagonal boron nitride
Abstract
The temperature dependence of the energy bandgap of hexagonal boron nitride (h-BN) has been probed via photoluminescence emission characteristics of a donor-to-acceptor pair transition in a 20-layer h-BN epilayer. The results indicate that the universal behavior of bandgap decreasing with temperature is absent in multi-layer h-BN. Below 100 K, the bandgap energy variation with temperature, Eg vs. T, is dominated by the electron-phonon coupling and conforms to the common behavior of redshift with an increase in temperature. At T > 100 K, the bandgap shows an unusual blueshift with temperature, which can be attributed to the unique behavior of the in-plane thermal expansion coefficient of h-BN that becomes negative above around 60 K. Although both graphite and h-BN have negative thermal expansion coefficients in a broad temperature range, graphite has a zero energy bandgap, which makes h-BN a unique semiconductor to exhibit this unusual temperature dependence of the energy bandgap.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Sep 25, 2017
- Source ID
- 10.1063/1.4994070
Entities
People
- Hongxing Jiang
- Jing Li
- Jingyu Lin
- X. Z. Du
Organizations
- Army Research Office
- Texas Tech University
- United States Department of Energy